/Engine/Plugins/Online/OnlineFramework/Source/Party/Public/Party/PartyTypes.h
enum ESocialPartyInviteFailureReason { Success = 0, NotOnline, NotAcceptingMembers, NotFriends, AlreadyInParty, OssValidationFailed, PlatformInviteFailed, PartyInviteFailed, InviteRateLimitExceeded, }